Our objectives are: (a) To define the metabolic differences between the brains of sleeping and waking rats and, particularly, to focus on changes, substances, and reactions specific to sleep; (b) To isolate and characterize substances in the cerebrospinal fluid of sleep-deprived and normal goats that induce sleep or wakefulness in rats and other experimental animals. For objective (a) we have developed a system of infusing radioactive metabolites into the lateral ventricles of unrestrained rats that have been maintained on a strict light-dark cycle. We monitor the EEG and EMG of these animals. Sleeping and waking animals are rapidly frozen in Freon and the brains analyzed. A phosphoprotein is under particular study because its labeling pattern varies with sleep and wakefulness under certain conditions. We shall also investigate protein synthesis in brain during sleep. An important series of studies will deal with the influence of the environmental, physiological, and emotional status of the animal on "sleep-wake" differences. The work in part (b) depends on the atraumatic harvesting of CSF from normal or sleep-deprived goats. This fluid is fractionated to yield preparations that are sleep-inducing for rats, or are excitatory. An excitatory factor has been isolated and purified. It is a peptide of molecular weight about 2,000 that is extremely rich in glutamic acid residues. The sleep-inducing substance has a molecular weight of about 500. We aim to purify these substances by various chromatographic, electrophoretic and other physical techniques that yield non-toxic preparations, and to determine their structure by amino acid analysis where appropriate, and by mass-spectrometry.